The present invention relates generally to imaging devices, and more particularly to a method and apparatus for simultaneously acquiring and processing image data.
Hospitals and other health care providers rely extensively on imaging devices such as computed tomography (CT) scanners, magnetic resonance imaging (MRI) scanners and positron emission tomography (PET) scanners for diagnostic purposes. These imaging devices provide high quality images of various bodily structures and functions. Each imaging device produces a different type of image based on the physics of the imaging process. For example, in a CT scanner, an x-ray source generates x-rays which propagate through the body and are detected by a detector on the other side of the body. The x-rays are attenuated to different degrees depending on what bodily structures they encounter, which results in an image showing the structural features of the body. CT scanners, however, are not particularly sensitive to biological processes and functions.
PET scanners, on the other hand, produce images which illustrate various biological process and functions. In a PET scan, the patient is initially injected with a radioactive substance known as a radiopharmaceutical. The radiopharmaceutical may be 18F-fluoro-2-deoxyglucose (FDG), for example, a type of sugar which includes radioactive fluorine. The radiopharmaceutical becomes involved in certain bodily processes and functions, and its radioactive nature enables the PET scanner to produce an image which illuminates those functions and processes. For example, when FDG is injected, it may be metabolized by cancer cells, allowing the PET scanner to create an image illuminating the cancerous region. PET scanners, however, do not generally provide structural details of the patient as well as other types of scanners such as CT and MRI scanners.
Recently PET-CT scanners have been introduced. A PET-CT scanner includes both a CT scanner and a PET scanner installed around a single patient bore. A PET-CT scanner creates a fused image which comprises a PET image spatially registered to a CT image. PET-CT scanners provide the advantage that the functional and biological features shown by the PET scan can be precisely located with respect to the structure illuminated by the CT scan. In a typical PET-CT scan, the patient first undergoes a CT scan, and then the patient undergoes a PET scan before exiting the scanner. After the CT and PET data have been acquired, the PET-CT scanner processes the data and generates a fused PET-CT image.
In PET-CT systems, the total effective examination time is the amount of time to acquire the PET and CT data, which may be significant, plus the amount of time to process the data. The data processing time after the CT and PET data have been acquired may also be significant, depending on the amount and type of data acquired. For PET-CT systems which perform 3D whole body (multiple frame) scans, the problem of long effective scan times can be exacerbated by the relatively long time it takes to process the 3D PET data.
The amount of time which a scanner takes to produce an image is very often an important consideration for hospitals and other health care providers in assessing the value of the scanner, particularly in the clinical environment. A scanner which can complete more scans per day is more valuable to the hospital than one which runs less efficiently, and therefore the hospital will be better able to justify the significant investment in a high-throughput scanner. In many existing PET-CT scanners, however, reconstruction times can be so long that 3D whole-body exams can become unacceptably long in clinical environments.
The present invention provides a method and apparatus for addressing these deficiencies.